Radiotelephone terminals typically include a radio transceiver integrated with a user interface mechanism within a handheld case. The user interface typically includes a plurality of keys similar to those provided. on conventional wireline telephones, as well as additional function keys for controlling functions associated with radiotelephone operations. The keys provide a means for entering commands, telephone numbers or other data for processing by the radiotelephone. A display may be used to display information a user has entered at the keys, e.g., telephone numbers, menu selections, and the like, as well as to display messages or other information received from a radiotelephone system with which the radiotelephone is communicating. The display may also be used to display information stored in memory located in the radiotelephone.
Commonly, the display is configured to display one or more graphical objects, e.g. a list of commands in a command menu or a list of telephone numbers that are stored in the radiotelephone memory that the user may select for communication. The graphical objects may be selectively displayed, for example, by displaying a selected number of entries in a list of telephone numbers or command options. The list may be "scrolled" in response to a user input to allow a large list to be displayed on a small display.
In some conventional radiotelephones, control of the scrolling of graphical objects on the display may be controlled by one or more keys, the operation of which may be similar to the "arrow" keys provided on computer keyboard. Other keys may be provided to invoke particular selections. In other conventional radiotelephone designs, a wheel-like input device may be mounted on the radiotelephone case that may be turned by a user to effect scrolling of graphical objects on the display. The wheel device may also be configured to select items on the display in response to user application of radial pressure to the wheel.
Each of these conventional techniques for control of a radiotelephone display has its limitations. Keys for scrolling and invoking display selections may be awkward to use, and may consume valuable space on the keypad of the radiotelephone. A wheeled input device may provide faster and more intuitive scrolling control, but such a device may take up an inordinate amount of space and require moving parts which may be more prone to failure. Accordingly, there is a need for improved input devices for radiotelephones.